It is known that some organic dye compounds induce a receptor potential responding to photostimulation in optic nerve, particularly retinal neuronal cells constituting optic nerve. There have been investigations for alternative retinal materials using such an organic dye compound. Patent Reference No. 1 has described an agent for inducing receptor potential containing an organic dye compound which induces a receptor potential responding to photostimulation in optic nerve. According to this, it is described that the agent for inducing receptor potential of the invention is very useful as a substituent material for visual-related substances in substituent materials for the retina such as an artificial retina for alleviating or eliminating visual disturbance caused by a retinal disorder associated with injury or sickness including visual field constriction, decreased vision and nyctalopia, and color anomaly caused by chemical addiction, neural disturbance of visual center, retinal disease and lack of a particular retinal cone. However, the amount of a dye fixed in fixing an organic dye compound to a substrate made of a polyethylene is not necessarily large, and improvement is needed.
Non-patent Reference No. 1 has described an artificial retina in which a dye is fixed to a polyethylene film. According to this document, the artificial retina was implanted under a retina of a retinitis pigmentosa model rat (RCS rat) and a behavior test of the rat was conducted, and as a result, vision was significantly improved in a rat implanted with the artificial retina under a retina, compared to a rat implanted with a polyethylene film without a fixed dye. However, in Non-patent Reference No. 1, a polyethylene film is reacted with a dye, washed with chlorobenzene, immersed in chlorobenzene for further 24 hours, and washed with water to produce an artificial retina. Such a washing process has a problem that washing with chlorobenzene causes dissociation of a dye chemically bonded to a polyethylene film. In particular, it takes a relatively long time to remove the unreacted dye which is not chemically bonded to the polyethylene film, and therefore, in addition to the unreacted dye, dissociation of the dye chemically bonded to the polyethylene film continuously occurs. As a result, completion of removal by washing of the unreacted dye cannot be determined, and thus, in the light of working margin, it is inevitable to take a very long washing time.